A week ago, on the night of the New Hampshire primary, Newt Gingrich stepped out of an SUV, his face grim, and stormed the Radisson hotel lobby in downtown Manchester. As he moved briskly toward the ballroom, he was swarmed by cameras and a bevy of reporters. In spite of his disappointing finish, he promised to “illustrate the difference” between him and Mitt Romney in the next battleground, the South Carolina primary on January 21. “It’s going to be a real choice between a Reagan conservative and a Massachusetts moderate,” he pledged.

In recent days, however, the South Carolina contest has become more than a contrast of politics, a “choice” between two candidates on substance and style. Instead, it has evolved (or devolved, depending on whom you ask) into a brutal, internecine GOP war.

On the trail, Gingrich continues to hammer Romney not so much for his positions but for his past, casting him as an aloof corporate raider. And on the Palmetto State airwaves, a pro-Gingrich super PAC is spending $3 million to underscore that theme, sponsoring a lengthy and controversial film, King of Bain, about job losses connected to Romney’s former firm.

As the primary approaches, Gingrich’s top backers, both inside and outside of the campaign, are counting on the scorched-earth maneuvers to pay off, and to lessen Romney’s growing aura of inevitability. In a state with high unemployment and a diminished manufacturing base, they say, it’s strategic to highlight Bain, and in a tough race, it’s more than fair to play hardball.

“This is going to be Armageddon,” Gingrich said last week in a CNN interview, predicting that Romney would attempt to secure the nomination with a South Carolina sweep. “They are going to come in here with everything they’ve got, every surrogate, every ad, every negative attack.”

The open question, Gingrich sources say, is whether the campaign can make its Bain blitz with precision, damaging Romney without destroying their own chances. It’s a risky play, says one longtime Gingrich adviser, but it has a big upside: If you beat Romney here, you’re a giant-killer.

R. C. Hammond, Gingrich’s campaign spokesman, largely concurs, and tells National Review Online that the former speaker will keep slinging arrows at Romney. “There is no way a moderate Republican like Romney will be able to beat Obama,” Hammond says, and he frames Gingrich’s critiques as an urgent reminder to conservatives about Romney’s vulnerabilities.

“Our job is to go out and make the case that Newt Gingrich is not only the conservative to beat Mitt Romney, he’s the conservative who can beat Obama,” Hammond says.

Indeed, to Hammond and others within the Gingrich camp, the candidate’s Bain-themed rhetoric is the keystone for their larger case. Hammond argues that there is a major gap “between what [Romney] says and reality,” and that to think Romney’s years at Bain will suddenly be an asset in November, after Democrats comb through the records, would be foolish. “It’s not Bain that’s the problem; it’s the narrative,” Hammond says. “[Romney] has a record, and he refuses to be accountable for it,” from his private-sector work to his gubernatorial decisions. “Romney has established his own conventional wisdom,” adds a senior Gingrich adviser. “Our job, in ads and on the stump, is to puncture it, and challenge his electability.”

But Gingrich’s virulent, anti-Bain message has soured Beltway Republicans. That was expected, campaign advisers say; the real worry is the potential outrage of South Carolina conservatives. Sen. Jim DeMint (R., S.C.), a tea-party favorite, has already spoken out against the pro-Gingrich super-PAC ads, calling them an unfair “character assassination” against Romney.

Further hints of a backlash have bubbled up at various campaign stops. Over the weekend, at a forum hosted by Mike Huckabee, Gingrich blasted Romney and Bain, telling assembled Republicans that at a closed steel mill, “capital wasn’t put at risk; capital was drained out of that company.” Several attendees “loudly booed” Gingrich’s remark, according to ABC News.

Hammond brushes aside concerns about the negative turn. “Mitt Romney, with his super PAC, threw this race into the gutter,” he says. “He won’t get away with what he did in Iowa.” Two fellow top staffers are also adamant about Gingrich’s right to take on Bain and Romney, but they note that Gingrich will wait to be asked about the topic in coming days; he won’t bring it up himself. On Sunday and Monday, they note, he mostly avoided addressing the issue.

And in Monday night’s Fox News debate, Gingrich defended his tack. “I raise questions that I think are legitimate questions,” he said. “Raising questions” about Romney’s Bain record is not “only the prerogative of Barack Obama” and Democrats. With Bain’s “pattern” of leaving companies with “enormous debt,” Republicans must scrutinize Romney’s role, he said.

Former congressman Chris Chocola, the president of the Club for Growth, a pro-market advocacy group, warns that Gingrich may not “get away” with his harsh words. The tough talk and super-PAC ads will generate headlines, Chocola says, but they’ll also eventually make conservatives uneasy about Gingrich, with “anti-Bain” translated as anti-capitalist. “It’s an angry response,” he says. “And it’s so universally discredited by everybody, as over the top and out of context, that in a strange way, it may inoculate Romney in the future, discrediting the charges.”

Grover Norquist, the president of Americans for Tax Reform, says Chocola is right, and that the super PAC’s 28-minute film about Bain — which contains factual inaccuracies, according to the Washington Post — is “fact-checking the Obama attacks for Obama.” Beyond that, “I have no idea” what Gingrich is doing, Norquist says, unless “in the middle of a primary, you . . . convince yourself that the other guy can’t win, so you’re not damaging him for the general; you tell yourself you’re trying to save the Republican party.”

Team Gingrich is not fretting; in fact, they see a glimmer of opportunity. South Carolina polls, for the moment, show Gingrich above water, a steady second in most surveys. An American Research Group survey shows Romney leading Gingrich 29 percent to 25 percent among likely GOP voters, which is within the margin of error. Rasmussen’s latest poll shows Romney leading 28 percent to 21 percent. Both polls put Gingrich ahead of Rick Santorum and Ron Paul.

Still, should Gingrich stumble on Saturday, finishing a distant second or third, there will be a clamor for him to withdraw, says one source close to the campaign, especially because of the campaign’s rough-and-tumble play for South Carolina. But Gingrich may not immediately bow out even in this situation, the source says. “There are many factors that will play a part in the decision, including whether Ron Paul fizzles in South Carolina,” the source says. “If [Paul] fades, Romney wins, and Gingrich gets the silver, he’ll fight on, with enough fuel for Florida.”

Others within Gingrich’s circle are not as optimistic about the path forward should the campaign fail to catch fire. “He will need to win South Carolina,” says Jack Kimball, a former chairman of the New Hampshire GOP and a Gingrich surrogate. “If he does, that will be a game-changer, but he will need that, he will need the momentum.” Leading state GOP figures agree. “If Romney wins South Carolina, I think the game is over,” said Rep. Tim Scott (R., S.C.) on NBC’s Meet the Press. “This is the last stand for many candidates.” On the same program, Sen. Lindsey Graham (R., S.C.) echoed Scott, and said Republicans will “rally” to Romney if he wins this week.

Gingrich acknowledges the importance of winning South Carolina, and he promises to “reassess” his campaign should Romney emerge as the victor. But for now, in the middle of a primary dogfight, he will remain the king of pain, the anti-Bain crusader. As he told reporters in Rock Hill, S.C., late last week, “I’m prepared to have people be irritated on the right and the left.”